The present invention relates generally to communication systems, and more particularly to interfacing multiple protocol stacks within a network device.
In today""s information age, it is common for computers and computer peripherals to be internetworked over a communication network. The various network devices in the communication network communicate using various protocols.
Within a particular network device, the various protocols are organized into one or more protocol stacks. A protocol stack is essentially a grouping of related protocols. Each protocol of a protocol stack operates at a particular layer of the protocol stack. A protocol operating at a particular layer of the protocol stack provides services to protocols at the next higher layer in the protocol stack and consumes services provided by protocols at the next lower layer in the protocol stack.
In certain networking situations, it is necessary or desirable for protocol messages to be exchanged between protocol stacks of the network device. Typically, this is accomplished by associating each protocol stack with a network interface and providing a connection between the various network interfaces over which protocol messages can be exchanged. For example, the various network interfaces may be connected using a crossover cable or a local area network (LAN). In any case, this connection is external to the network device.
This technique for interfacing protocol stacks has a number of drawbacks. For one, any network interfaces that are utilized for interfacing protocol stacks are not available for other networking functions. Also, installation and maintenance of the external connection adds complexity and cost.
Thus, a technique for interfacing protocol stacks that does not utilize network interfaces and does not require any external connections is needed.
In accordance with one aspect of the invention, a virtual circuit subsystem is used to interconnect protocol stacks internally within a network device. The virtual circuit subsystem establishes a virtual connection between at least a first protocol of a first protocol stack and a second protocol of a second protocol stack. The virtual circuit subsystem enables messages to be exchanged between the first protocol of the first protocol stack and the second protocol of the second protocol stack over the virtual connection. Specifically, the virtual circuit subsystem converts a transmitted message received from the first protocol into a received message for the second protocol, and converts a transmitted message received from the second protocol into a received message for the first protocol. Thus, the virtual circuit subsystem eliminates the need to connect protocol stacks externally.